Flue Exhaust Fan with Configurable Outlet

ABSTRACT

A flue exhaust fan has a configurable upwardly facing outlet for delivery of a mixture of gas and ambient air from the water heater or a furnace into either a vertical flue or a horizontal flue. Because the horizontal flue necessarily includes a 90° transition between the upwardly facing outlet and the horizontal flue, the horizontal flue has a greater flow resistance than the vertical flue. By installing a straight connector with a flow resistance element, the gas flow resistance encountered by the flue exhaust fan is the same for a vertical flue and a horizontal flue therefore requiring a single flue exhaust fan with a flow rating for installation with a horizontal flue or a vertical flue.

FIELD OF THE INVENTION

This invention relates to a flue exhaust fan for a water heater or a furnace that employs a fan to draw ambient air and flue gases into a mixing chamber where the ambient air and flue gases are mixed. The fan forces the mixture of ambient air and flue gases from the mixing chamber, through an upwardly facing fan outlet, and into an attached flue.

BACKGROUND OF THE INVENTION

In some water heater or furnace installations, the flue is vertical, and the upwardly facing fan outlet can be connected directly to the vertical flue. In other installations, the flue is horizontal, and the upwardly facing fan outlet is connected to the horizontal flue by means of a 90° adapter connected between the upwardly facing fan outlet and the horizontal flue.

A flue exhaust fan generally is rated for a certain gas flow rate into the flue. Where the exhaust fan is connected directly to the vertical flue, the flue exhaust fan encounters a particular gas flow resistance. Alternatively, when the flue exhaust fan is connected to a horizontal flue through a 90° adapter, the flue exhaust fan encounters a gas flow resistance that is higher than the gas flow resistance encountered with a vertical flue, and a higher flow rate fan is required for the horizontal flue.

For either a vertical flue or a horizontal flue, the connection from the upwardly facing fan outlet and the flue must accommodate condensate that forms on the cooler internal surfaces of the flue and the connector between the upwardly facing fan outlet and the flue. Particularly, the condensate should not be allowed to drip into the exhaust fan housing.

SUMMARY OF THE INVENTION

The flue exhaust fan with configurable outlet in accordance with the present invention overcomes the problems identified above. Particularly, the configurable outlet of the flue exhaust fan has a straight connector for connecting the upwardly facing fan outlet of the flue exhaust fan to a vertical flue and a 90° connector for connecting the upwardly facing fan outlet of the flue exhaust fan to a horizontal flue.

The 90° connector increases the resistance to gas flow from the flue exhaust fan outlet into the horizontal flue. Consequently, the flue exhaust fan is rated to provide the required gas flow into the horizontal flue in view of the increased gas flow resistance created by the 90° connector. In order to use the same flue exhaust fan with the same gas flow rating for a vertical flue and provide the same gas flow into the vertical flue, the straight connector must provide approximately the same resistance to gas flow as the 90° connector. In order to balance the gas flow into the vertical flue as well as the horizontal flue, the flue exhaust fan is rated to meet the gas flow requirements for the horizontal flue and 90° connector. When the same flue exhaust fan is used with the straight connector, the straight connector has an internal resistance element that creates gas flow resistance similar to that of the 90° connector. Because the straight connector and the 90° connector provide the same amount of gas flow resistance, a single flue exhaust fan can be used for either a vertical flue installation or a horizontal flue installation.

The resistance element in the straight connector is a concentric insert positioned inside the straight connector that restricts the flow of flue gases from the upwardly facing fan outlet into the vertical flue. The resistance element is sized to match the gas flow resistance of the straight connector to the gas flow resistance of the 90° connector.

In connection with either a vertical flue or horizontal flue, condensate forms on the internal surfaces of the flue and connectors and flows back toward the upwardly facing fan outlet of the flue exhaust fan. The straight connector and the 90° connector both have a condensate management system for collecting the condensate and draining the condensate so the condensate does not enter the fan housing through the upwardly facing fan outlet. The condensate management system includes an annular groove created around the inlet perimeter of the connector and the perimeter of the upwardly facing fan outlet of the fan housing. A drain tube communicates with the annular groove in order to deliver the condensate to a location remote from the flue exhaust fan housing.

Further objects, features and advantages will become apparent upon consideration of the following detailed description of the invention when taken in conjunction with the drawings and the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top perspective view of a conventional flue exhaust fan.

FIG. 2 is a bottom perspective view of the conventional flue exhaust fan.

FIG. 3 is a perspective view of a modified upper fan housing for the flue exhaust fan, which modified upper fan housing forms part of the present invention.

FIG. 4 is a perspective view of the modified upper fan housing for the flue exhaust fan with a 90° connector attached in accordance with the present invention.

FIG. 5 is a side section view of the modified upper fan housing for the flue exhaust fan with the 90° connector attached in accordance with the present invention.

FIG. 6 is an end section view of the modified upper fan housing for the flue exhaust fan with the 90° connector attached in accordance with the present invention.

FIG. 7 is a perspective view of the 90° connector in accordance with the present invention.

FIG. 8 is a bottom plan view of the 90° connector in accordance with the present invention.

FIG. 9 is a side elevation view of the 90° connector in accordance with the present invention.

FIG. 10 is a side section view of the 90° connector in accordance with the present invention.

FIG. 11 is a perspective view of the modified upper fan housing for the flue exhaust fan with a straight connector attached in accordance with the present invention.

FIG. 12 is a side section view of the modified upper fan housing for the flue exhaust fan with the straight connector attached in accordance with the present invention.

FIG. 13 is an end section view of the modified upper fan housing for the flue exhaust fan with the straight connector attached in accordance with the present invention.

FIG. 14 is a perspective view of the straight connector in accordance with the present invention.

FIG. 15 is a side perspective view of the straight connector in accordance with the present invention.

FIG. 16 is a top plan view of the straight connector in accordance with the present invention.

FIG. 17 is a bottom plan view of the straight connector in accordance with the present invention.

FIG. 18 is an end section view of the straight connector in accordance with the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 and FIG. 2 show a conventional flue exhaust fan 10 used in connection with a water heater or a furnace. The flue exhaust fan 10 has a fan housing 14 including an upper fan housing 16 and a lower fan housing 18. A squirrel cage fan 22 is mounted for rotation inside the fan housing 14. A motor 20 drives the squirrel cage fan 22. The upper fan housing 16 includes an upwardly facing fan outlet 30. The flue exhaust fan 10 includes a mixing chamber 28 with ambient air inlets 24 and a flue gas inlet 26. The flue exhaust fan 10 is mounted to a water heater or a furnace so that the flue of the water heater or furnace communicates with the flue gas inlet 26 of the flue exhaust fan 10.

In operation, the fan 22 draws flue gas from the water heater or furnace through the flue gas inlet 26 and into the mixing chamber 28. Simultaneously, the fan 22 draws ambient air through the ambient air inlets 24 into the mixing chamber 28 where the ambient air and the flue gases mix. The fan 22 then forces the mixture of ambient air and flue gas out of the fan housing through the upwardly facing fan outlet 30. The upwardly facing fan outlet 30 is sized to connect directly to a vertical flue. In a conventional installation, where a horizontal flue is present, a 90° adapter connects the upwardly facing fan outlet 30 to the horizontal flue. Similarly, the upwardly facing fan outlet 30 is sized to accept the 90° adapter which in turn is sized to fit the horizontal flue.

As previously noted, the 90° adapter increases the gas flow resistance presented at the upwardly facing fan outlet 30 as compared to the gas flow resistance presented by the straight connection to the vertical flue.

In accordance with the present invention, FIG. 3 shows a modified upper fan housing 32 with a modified upwardly facing fan outlet 34. In all other respects, the flue exhaust fan 10 is the same as previously described. The modified upwardly facing fan outlet 34 is sized to be compatible with either a straight connector inlet 42 of a straight connector 40 (FIG. 12) or a 90° connector inlet 48 of a 90° connector 46 (FIG. 4). The straight connector 40 is employed for connection of the flue exhaust fan 10 to a vertical flue, and the 90° connector 46 is employed for connection of the flue exhaust fan 10 to a horizontal flue.

The 90° connector 46 (FIGS. 4-10) comprises a 90° connector wall 47 that creates an enclosed unrestricted 90° passage 51 between the 90° connector inlet 48 and a 90° connector outlet 50. The 90° connector inlet 48 is sized to fit and connect to the modified upwardly facing fan outlet 34 as shown in FIGS. 4-6. The 90° connector outlet 50 is sized to fit and connect to a standard horizontal flue. Once installed, the 90° connector 46 and the horizontal flue present a first gas flow resistance to the flue exhaust fan 10. While the above description refers to a 90° connector, the present invention also contemplates the use of other angled connectors such as a 45° connector, a 60° connector, a 30° connector, or connectors with other angles.

The straight connector 40 (FIGS. 11-18) comprises a straight connector wall 41 that creates an enclosed straight passage 45 between the straight connector inlet 42 and a straight connector outlet 44. The straight connector inlet 42 is sized to fit and connect to the modified upwardly facing fan outlet 34 as shown in FIGS. 11-13. The straight connector outlet 44 is sized to fit and connect to a standard vertical flue. Once installed, the straight connector 40 and the vertical flue present a second gas flow resistance to the flue exhaust fan 10.

In order to match the first gas flow resistance of the 90° connector 46 (or other angled connector) to the gas flow resistance of the straight connector 40, a resistance element 52 is positioned in the passage 45 of the straight connector 40 and held in place by mounting brackets 55. The resistance element 52 is generally circular in cross-section and comprises a resistance element wall 57 that creates an enclosed resistance element passage 61 between a resistance element inlet 53 and a resistance element outlet 54. The resistance element wall 57 slants outwardly toward the resistance element inlet 53. While the resistance element 52 is illustrated as having generally a circular cross-section, other geometric cross-sections may be used. The resistance element inlet 53 generally has a larger cross-sectional area than the cross-section area of the resistance element outlet 54. While generally the resistance element inlet 53 has a larger cross-sectional area than the cross-sectional area of the resistance element outlet 54, the cross-sectional areas could be equal. The cross-sectional area of the resistance element inlet 53 cannot be smaller than the cross-sectional area of the resistance element outlet 54 due to condensation draining risks of that configuration. By adjusting the cross-sectional areas of the resistance element inlet 53 and the resistance element outlet 54, the straight connector 40 can be tuned so that the second gas flow resistance presented to the flue exhaust fan 10 will be approximately equal to the first gas flow resistance presented to the flue exhaust fan 10 by the 90° connector 46 and horizontal flue. Consequently, because the first gas flow resistance of the 90° connector 46 and the horizontal flue is essentially equal to the second gas flow resistance of the straight connector 40 and vertical flue, a single flue exhaust fan 10 can be manufactured and stocked for installation for either a vertical flue or a horizontal flue.

The 90° connector 46 includes a condensate management system 58, and the straight connector 40 includes a similar condensate management system 59. As best shown in FIGS. 5-6, the 90° connector 46 when connected to the modified upwardly facing fan outlet 34 creates an annular groove 60 around the periphery of the modified upwardly facing fan outlet 34. As shown in FIG. 6, a drain tube 64 formed in the 90° connector 46 communicates with the annular groove 60. As water vapor enters the 90° connector 46 and the connected horizontal flue from the flue exhaust fan 10, condensate forms on the inner surface of the wall 47 of the passage 51 of the 90° connector 46 and the inner surface of the horizontal flue. The condensate flows along the inner surfaces of the 90° connector 46 and the horizontal flue, collects in the annular groove 60, flows out of drain tube 64, and flows away from the fan housing 14 of the flue exhaust fan 10.

As best shown in FIGS. 12-13, the straight connector 40 when connected to the modified upwardly facing fan outlet 34 creates an annular groove 62 around the periphery of the modified upwardly facing fan outlet 34. As particular shown in FIG. 13, a drain tube 66 formed in the straight connector 40 communicates with the annular groove 62. As water vapor enters the straight connector 40 and the connected vertical flue from the flue exhaust fan 10, condensate forms on the inner surface of the wall 41 of the passage 45 of the straight connector 40, and on the inner and outer surfaces of resistance element wall 57, and the inner surface of the vertical flue. The condensate flows along the inner surfaces of the straight connector 40 and the vertical flue, collects in the annular groove 62. Because the outlet end of the resistance element wall 57 is aligned with the annular groove, the condensate formed on the resistance element wall 57 tends to drip into the annular groove 62. Once the condensate has been collected by the annular groove 62, the condensate flows out of drain tube 66, and flows away from the fan housing 14 of the flue exhaust fan 10.

While this invention has been described with reference to preferred embodiments thereof, it is to be understood that variations and modifications can be affected within the spirit and scope of the invention as described herein and as described in the appended claims. 

I claim:
 1. A flue exhaust fan with a rated gas flow for connection to a flue comprising: a. a fan housing; b. an upwardly facing outlet from the fan housing, the upwardly facing outlet configured to connect compatibly to: i. an angled connector with an angled connector inlet for connecting the upwardly facing outlet to a horizontal flue, the angled connector having a first gas flow resistance; or ii. a straight connector with a straight connector inlet for connecting the upwardly facing outlet to a vertical flue, the straight connector including a resistance element to produce a second gas flow resistance for the straight connector, wherein the rated gas flow of the flue exhaust fan matches the first gas flow resistance of the angled connector and matches the second gas flow resistance of the straight connector.
 2. The flue exhaust fan of claim 1, wherein the resistance element is located inside the straight connector and has a resistance element inlet, a resistance element outlet, and resistance element wall connecting the resistance element inlet and resistance element outlet and wherein the cross-sectional area of the resistance element inlet is greater than or equal to the cross-section area of the resistance element outlet.
 3. The flue exhaust fan of claim 2, wherein the upwardly facing outlet of the fan housing includes an annular groove at an intersection between the straight connector inlet of the straight connector and wherein the annular groove is connected to a drain tube for draining condensate out of the straight connector.
 4. The flue exhaust fan of claim 3, wherein the straight connector has a straight connector wall and the resistance element is located inside the straight connector and offset from the straight connector wall so that condensate can flow along the straight connector wall and into the annular groove.
 5. The flue exhaust fan of claim 4, wherein the resistance element wall flares outwardly toward the resistance element inlet to align with the annular groove so that condensate on the resistance element wall drips into the annular groove.
 6. The flue exhaust fan of claim 1, wherein the upwardly facing outlet of the fan housing includes an annular groove at an intersection between an angled connector inlet of the angled connector and wherein the annular groove is connected to a drain tube for draining condensate out of the angled connector.
 7. A flue exhaust fan for connection to a flue comprising: a. a fan housing; b. an upwardly facing outlet from the fan housing, the upwardly facing outlet configured to connect compatibly to a flue connector, wherein the upwardly facing outlet of the fan housing includes an annular groove at an intersection between the upwardly facing outlet and the flu connector and wherein the annular groove is connected to a drain tube for draining condensate out of the flue connector.
 8. A straight connector for connecting an upwardly facing fan outlet of a flue exhaust fan to a flue, the straight connector comprising: a. a straight connector inlet, a straight connector outlet, and a straight connector wall forming an enclosed straight connector passage through the straight connector between the straight connector inlet and the straight connector outlet; b. a resistance element located inside the straight connector passage and having a resistance element inlet with a resistance element inlet cross-sectional area, and resistance element outlet with a resistance element outlet cross-sectional area, and a resistance element wall connecting the resistance element inlet and the resistance element outlet.
 9. The straight connector of claim 8, wherein the resistance element inlet cross-sectional area is greater than or equal to the resistance element outlet cross-sectional area.
 10. The straight connector of claim 8, wherein the upwardly facing outlet of the fan housing includes an annular groove at an intersection between the straight connector inlet of the straight connector and wherein the annular groove is connected to a drain tube for draining condensate out of the straight connector.
 11. The straight connector of claim 10, wherein the resistance element of the straight connector is offset from the resistance element wall so that condensate can flow along the resistance element wall and into the annular groove.
 12. The straight connector of claim 11, wherein the resistance element wall flares outwardly toward the resistance element inlet to align with the annular groove so that condensate on the resistance element wall drips into the annular groove. 